The episode opens with the Walmington-on-SeaHome Guard unit in Eastgate cinema, watching a film about Napoleon. A panning shot moves across the faces of the platoon while they are watching, Mainwaring looking superior, Wilson looking bored, Frazer muttering "rubbish", Pike sucking his thumb, Godfrey asleep, Walker with his arms around a blonde girl, Jones looking dreamy ... At the end of the film the National Anthem begins, but the platoon all stampede out apart from Mainwaring who gets knocked over in the rush but struggles up to stand to attention while the anthem plays to a now empty cinema.

The platoon is next seen on the upper deck of a bus going back to Walmington. Mainwaring asks the platoon what they thought of the film. Sponge says they should have sat at the front as he couldn't see. Mainwaring says he was disappointed - he thought the film would have been about strategy and tactics but consisted of Greta Garbo being chased around a four poster bed. Walker replies that that is strategy and tactics.

Wilson and Mainwaring are given their tickets by an attractive bus conductress who Mainwaring takes a fancy to, and when Walker, Pike and Jones start larking about then singing the lewd song "Roll Me Over In The Clover" Mainwaring stops them and apologises to the bus conductress, who is grateful and says he is "very gallant". Warden Hodges arrives, and teases the platoon for going to the cinema and not being ready for Hitler. Whilst buying a ticket he asks the bus conductress for a "tickle at the terminus". Mainwaring is furious and intervenes again, and is thanked by the bus conductress. Mainwaring then instructs the platoon that after their disgraceful behaviour in the cinema, they are to let him go off the bus first and in an orderly fashion. When the bus stops at Walmington, Hodges lets him get halfway down the bus then shouts "It's closing time in five minutes", thus causing Mainwaring to get knocked over again in the stampede as the platoon rush for the pub.

Later, the platoon are on parade. Frazer gives a long rambling explanation of how he complained to the manager about the "sheer historical inaccuracies of the film", but eventually admits sheepishly that he got his money back. Mainwaring berates them for the two examples of bad behaviour. They apologise, but he responds by saying that "fine words butter no parsnips". This provokes a discussion in the ranks, about how you can't get butter, or parsnips, with Walker offering to obtain both, until he says that the platoon will have to stand to attention whilst Sergeant Wilson plays the National Anthem on the gramophone 6 times. They stand to attention, but Wilson plays the German National Anthem "Deutschland Uber Alles" by mistake, and is half asleep so Mainwaring has to shout at him to take it off. He and Wilson go to Mainwaring's office, where they find the vicar at his desk, who refuses to get out of the way for Mainwaring. Whilst Jones continues to play the National Anthem at an increasing speed, Mainwaring and the vicar have to stand, then race to sit on the chair, like musical chairs.

The next scene is in Mainwaring's office after the parade. Walker arrives and gives Sgt Wilson two bottles of Black Marketstout, and presents Mainwaring with some similarly sourced cheddar cheese. Mainwaring excuses this to Wilson by saying it is for his vegetarian wife. He rings her to spring this 'toasted cheese supper' surprise on her, but she gets the wrong idea on the phone and says she has a headache and is going to bed. Mainwaring is disappointed, but Wilson suggests they eat the cheese between them. Mainwaring is touched, then Jones arrives and, tempted by the cheese, offers some kidneys if he can join them. Cut to the end of the feast, when Jones tells a wonderful rambling story about a native girl he nearly married in the Sudan. Mainwaring leaves to go home, suggesting that the bus conductress they met earlier wouldn't have turned down a toasted cheese supper.

The next scene is in Mainwaring's Anderson shelter in his garden. He is having a restless night after eating the (rather indigestible) meal with Wilson and Jones. He takes some bismuth (indigestion) tablets.

The scene now shifts, and we see Mainwaring dreaming that he is Napoleon at the Battle of Waterloo. It features the rest of the cast in various roles, including Wilson as Wellington, flanked by Frazer as Gordon of the Highlanders and Hodges as a senior officer. Walker is "Captain Gerald" in the cavalry, Jones is a French Corporal, Pike is a French drummer boy and Godfrey is a French artillery man. Many catch phrases and actions are used: "put those lights out", "you stupid drummer boy", Private Godfrey's upside down cakes, "Oi, Napoleon", and also some phrases from earlier in the episode such as Sponge saying "we should have sat down the front, in the ninepennies" when Mainwaring complains that he can't see the battle. At the surrender, Wilson acts very superior, for instance asking Mainwaring for his full name and address, and refusing to let Mainwaring borrow his pen. Mainwaring says farewell to his troops, with great comic effect. Hodges then tells the troops that the Duke will buy them all a drink, and in the stampede they knock Mainwaring over into the mud like they did in the cinema and bus.

Mainwaring is next seen just before being exiled to Elba, standing next to the bus conductress, who is dressed as Marie Walewska (Napoleon's mistress). [1] They exchange farewells, then Mainwaring wakes up, to find that he has overslept and he has a rude note from his wife complaining that he didn't come home last night.

The episode copied some details from the 1970 feature film Waterloo: the scene where Napoleon kisses the flag, and incorrectly showing Colonel Alexander Gordon, 4th Duke of Gordon as fighting at Waterloo (played by Frazer in the dream sequence).

Napoleon Bonaparte was in fact exiled to Elba before the Battle of Waterloo. After this defeat, he was imprisoned on the island of St Helena.

This episode is the closest we ever get to seeing Mrs. Mainwaring, when we see her very large posterior hanging down in the bunk above Mainwaring in the Anderson shelter.

This is one of two episodes which rather whimsically showed the Dad's Army characters in a historical setting; the other was The Two and a Half Feathers.